plmboxes: Multibox plots
In regr0: Building regression models

Description Usage Arguments Details Value Author(s) See Also Examples

Draw multibox plot(s) for given (grouped) values, possibly asymmetric. 'plbox' draws a single multibox plot (low level graphical function). 'plboxes' is a high level graphics function that draws multiboxes for grouped data. A secondary, binary grouping factor can be given to produce asymmetric multiboxes.

plmboxes(formula, data, width=1, at=NULL,
    probs=NULL, outliers=TRUE, na=FALSE,
    refline=NULL, add=FALSE, ilim=NULL, ilimfac=4, ilimext=0.05,
    xlim=NULL, ylim=NULL, axes=TRUE, xlab=NULL, ylab=NULL,
    labelsvert=FALSE, mar=NULL,
    widthfac=NULL, minheight=NULL, colors=NULL, lwd=NULL, ...)
plmbox(x, at=0, probs=NULL, outliers=TRUE, na.pos=NULL, width=1, wfac=NULL,
    minheight=NULL, adj=0.5, extquant=TRUE, ilim=NULL, ilimext=0.05, 
    widthfac=c(max=2, med=1.3, medmin=0.3, outl=NA),
    colors=c(box="lightblue2",med="blue",na="gray90"),
    lwd=c(med=3, range=2), warn=options("warn"))

`formula`	a formula, such as 'y ~ grp' or 'y~grp+grp2', where 'y' is a numeric vector of data values to be split into groups according to the grouping variable 'grp' (usually a factor) and, if given, according to the binary variable 'grp2'. 'y~1+grp2' produces a single asymmetric mbox.
`data`	a data.frame from which the variables in 'formula' should be taken.
`width`	a vector giving the widths of the multibox plot for each group 'grp1'.
`at`	horizontal position of the multiboxes. Must have length equal to the number of (present) levels of the factor 'grp'. if an element of 'at' is 'NA', the group will be skipped. Defaults to 1, 2, ...
`probs`	probability values for selecting the quantiles. If all 'probs' are <=0.5, they will be mirrored at 0.5 for 'plmboxes'. The default is c(0.05,0.25,0.5) if the average number of data per group (for 'plmboxes', or the number of data, for 'plmbox') is less than 20, c(0.025,0.05,0.125,0.25,0.375,0.5), otherwise.
`outliers`	logical: should outliers be marked?
`na, na.pos`	if 'na' is not NULL, NA values will be represented by a box. If 'na' is TRUE, the position of the box will be generated to be below the minimum of the data. If 'na' (for 'plmboxes') or 'na.pos' (for 'plmbox') is a scalar or a vector of length 2, the position of the box is at that value (with a generated width) or between the 2 values, respectively.
`refline`	vertical positions of any horizontal reference lines
`add`	logical. If TRUE, the mboxes will be added to an existing plot without calling 'plot'.
`ilim`	limits for ordinary plotting (in vertical direction). Beyond these limits, boxes are shown in the margins with squeezes scale. Note that the width of the boxes will not be adjusted to the squeezed scale, such that areas are no longer proportional to probabilities.
`ilimfac`	scalar factor by which the range 'middle range' interval is expanded, see `?pllimits`
`ilimext`	number ruling the amount of expansion of the vertical plotting range beyond the range of the data values (or `ilim` if used): the data range will be extended by the factor 'ilimext' in both directions.
`xlim`	plotting limits for the horizontal axis.
`ylim`	plotting limits for the vertical axis.
`axes`	logical. If FALSE, no axes are drawn.
`xlab`	label for the x axis. Defaults to the "x factor" – the first name on the right hand side of 'formula'
`ylab`	label for the x axis. Defaults to the left hand side of 'formula'.
`labelsvert`	logical: Should the labels for the level of the "x factor" be marked in vertical direction?
`mar`	plot margins. Default tries to be suitable.
`widthfac`	named vector used to modify the following settings: max=2: determes the maximal width of the boxes. Boxes that should be wider are censored and marked as such. med=1.3, medmin=0.3: determine the width of the mark for the data median. The width is 'med' times the maximal width of the boxes, but at least 'medmin'. outl=NA: length of the marks for outliers. sep=0.003: width of the gap between the "half" mbox plots in case of asymmetric mboxes (only needed for 'plmboxes'). For 'plmboxes', the argument needs to contain only the elements that should be different from the default values.
`colors`	named vector or list selecting the colors to be used, with named elements: box="lightblue2": color with which the central box(es) (those corresponding to probabilieties between 0.25 and 0.75) will be filled. med="blue": color of the mark for the median. na="grey90": color with which the box for NA values will be filled. For 'plmboxes', the argument needs to contain only the elements that should be different from the default values.
`lwd`	named vector or list selecting the line width to be used, with named elements: med=3: line width for the mark showing the median range=2: line width for the line along the range of the data For 'plmboxes', the argument needs to contain only the elements that should be different from the default values.
`...`	additional arguments passed to 'plot'

Specific arguments for 'plmbox':

`x`	vector (for symmetric mbox plot) or matrix with 2 columns (for asymmetric mbox plot) of data
`wfac`	factor by which the widths of the boxes must be multiplied. If given, it overrides 'width'
`minheight`	minimal class width ("height") for the boxes (in case two quantiled are [almost] identical). The default is 0.02 times the (median of the within group) IQR.
`adj`	adjustment of the boxes. 'adj=0' leads to boxes aligned on the left, 'adj=1', on the right, 'adj=0.5', centered. Other values of 'adj' make little sense.
`extquant`	logical, passed to `quinterpol`: Should the quantiles be extrapolated beyond the range of the data?
`warn`	level of warning for the case when there is no non-missing data

A multibox plot is a generalization (and modification) of the ordinary box plot that draws more details of the distribution in the form of a histogram with variable class widths. The classes are selected such that preselected quantiles form the class breaks. By default, these quantiled include the median and the quartiles, thereby recovering the box of the traditional box plot.

plmboxes invisibly returns the 'at' values that are finally used.\ plmbox returns a factor [to be defined...!!!] and, as attributes, the quantiles and widths used to draw the boxes

Werner A. Stahel

boxplot

plmboxes(Sepal.Length~Species, data=iris)
plmboxes(Sepal.Length~Species, data=iris,
  widthfac=c(med=2), colors=c(med="red"))

data(anorexia, package="MASS")
dd <- anorexia
dd[sample(nrow(dd),5),"Postwt"] <- NA
t.wtmed <- median(dd$Prewt)
plmboxes( I(Postwt-Prewt)~Treat + I(Prewt>t.wtmed) , data=dd,
         probs=c(0.1,0.25), na=TRUE)